The present invention relates to a liquid filling valve which is used to fill a vessel with a liquid, and in particular, to the construction of a filled liquid passage which is formed inside the valve.
A liquid filling valve generally comprises a pipe-shaped nozzle having a liquid pouring port at its bottom end, an operating rod passing through the nozzle in an elevatable manner and carrying a valve element toward its bottom end, and elevating means such as a cylinder which causes the operating rod to be driven up and down. By driving the operating rod down and up, the valve element which is carried by the operating rod at its bottom end can be caused to be seated upon a tapered valve seat which is formed in the bottom end of the filled liquid passage or to be removed therefrom, thus closing or opening the filled liquid passage.
In a conventional liquid filled valve as mentioned above, there has been a problem that at the commencement or termination of a filling operation, or immediately after the valve element has been removed from or immediately before the valve element is seated on the valve seat, the filled liquid passage is rapidly throttled to increase the flow speed of the liquid, causing a liquid splash or a bubbling within the vessel. In addition, in an above-the-mouth filling operation, there is also another problem that the splashed liquid may contaminate the outer surface of the vessel or the environment.
It is also to be noted that in the liquid filling valve as noted above, the operating rod is driven up and down through its connection with an air cylinder which is located above. Accordingly, a filled liquid (liquid to be filled) is introduced into the filled liquid passage through a lateral liquid feed pipe which is connected to the pipe-shaped nozzle. When a liquid is introduced laterally into the vertically disposed nozzle through which the operating rod extends centrally, the liquid flows down the filled liquid passage vortically to be filled into a vessel from the pouring port which is located toward the bottom end of the nozzle. There arises a problem then that the filled liquid is splashed around as it is projected from the pouring port as a vortical flow.
With a liquid filling valve as mentioned above where the liquid flowing out of the pouring port may be splashed, an above-the-mouth filling operation in which the filling operation takes place while maintaining the nozzle end above the mouth of the vessel is impossible. Where the liquid to be filled contains large particles as occurs in a fruit juice admixed with a pulp, the use of a metal meshwork to prevent a liquid splash is inhibited because the meshwork around the pouring port experiences a plugging.
The present inventor has previously filed a patent application for an invention which eliminates such difficulty (see Japanese Laid-Open Patent Application No. 9-255,095). In that invention, the valve comprises a tubular nozzle having an internal filled liquid passage, an operating rod passing through the tubular nozzle and driven up and down by elevating means, and an opening/closing valve including a valve element mounted on the bottom of the operating valve and a valve seat formed on the internal surface of the nozzle at the bottom end thereof. More specifically, the internal surface of the tubular nozzle has formed toward its top end a portion of a reduced diameter which gradually reduces the cross-sectional area of the filled liquid passage in a downward direction, and a portion of an increased diameter which is located below the portion of the reduced diameter and which gradually increases the cross-sectional area of the filled liquid passage in a downward direction. A portion of a constant internal diameter is formed on the internal surface of the nozzle in a region between the portion of the increased diameter and the opening/closing valve which is located therebelow, and a plurality of axially extending straightening vanes are mounted on the external surface of the operating rod which corresponds to the portion of a constant diameter.
According to the invention disclosed in the cited Laid-Open Patent Application, the liquid which flows down inside the nozzle in a vortical flow is completely straightend to remove a vortex before it is projected from the liquid pouring port, thus preventing the liquid from being splashed around, suppressing an increase in the flow speed to prevent a liquid splash and also preventing a bubbling within the vessel.
However, according to the arrangement of the described invention, the internal surface of the nozzle is formed with a portion of a reduced diameter, through which the operating rod having straightening vanes mounted on its external surface extends. Accordingly, when the operating rod is to be withdrawn from within the nozzle for purpose of maintenance such as changing bellows, the operating rod must be constructed so that it can be disassembled into a plurality of portions. At this end, in the filling valve mentioned above, the operating rod comprises a plurality of members, which are connected together by threadable engagement.
However, when the operating rod comprises a plurality of members, which are connected together by threadable engagement, the sterilization of parts which are threaded together is poor and it takes time to disassemble and assemble these parts, leading to a poor capability of maintenance. In addition, when the parts are connected together by threadable engagement, there remains a problem that the parts may become loosened.